The present invention relates to a pattern features extracting apparatus and method wherein similar patterns such as a pair of Kanji characters which are composed of a number of strokes, may be clearly distinguished from each other for pattern recognition.
Conventionally, a pattern recognition method is proposed wherein various pattern features are extracted from an unidentified or unknown pattern so as to recognize the unknown input pattern, and each extracted pattern feature is compared with each reference pattern feature so as to obtain a similarity measure therebetween, thereby determining as the input pattern a reference pattern having a highest similarity measure. The pattern features include a length, a slope, and an intersection between two lines and a corresponding angle of pattern elements. Furthermore, darkness (density) which corresponds to a set of pattern elements in a sub-area of the pattern is used as a pattern feature. However, these pattern features are not effective to recognize such complicated patterns which have many character strokes and may be similar to each other. For example, Kanji patterns as shown in FIG. 13 have substantially the same degree of darkness in the sub-areas of these characters, thus disabling high rate recognition. In particular, when these Kanji characters are written by hand, and thereby inevitably include many deformation components, successful recognition is almost impossible.
A method called as a multiple similarity method is described in U.S. Pat. No. 3,688,267. This method is very effective for pattern recognition when noise components such as stains or scratches are present. However, even if this method is applied to pattern recognition to Kanji characters, recognition cannot be successfully performed.